The present invention relates to the carburetors for so-called stratified charge combustion engines in which charges of lean air-fuel mixture and rich air-fuel mixture are fed to the combustion chamber of an engine, the rich air-fuel mixture is ignited and the resulting combustion flame leads to the combustion of the whole air-fuel mixture.
The carburetor for feeding the air-fuel mixture to the stratified charge combustion engine should produce the lean air-fuel mixture and the rich air-fuel mixture separately from each other, and further, the respective air-fuel mixtures should be varied dependent upon the operating conditions of the engine, that is, mainly upon the flow rate of intake air of the engine, and indirectly upon the opening degrees of throttle valves.
In order to meet the above requirements, in the specification of Japanese Patent Application No. 105998/75 there has been proposed a carburetor for the stratified charge combustion engine in which a supply of fuel from a fuel pressure control valve for changing pressure difference between the portions upstream and downstream of a metering jet in response to the variation of negative pressure generated at a venturi portion of an air intake passage, is supplied to a main discharge valve and an auxiliary discharge value respectively provided in a main air intake passage and an auxiliary air intake passage both disposed downstream of the venturi portion of said intake passage, by being devided while passing through flow division control means including a jet needle and a jet needle orifice and controlled in proportion to the movements of a main throttle valve and an auxiliary throttle valve respectively provided in said main and auxiliary intake passages and linked with each other.
With the arrangement described, theoretically highly accurate control can be expected. However, in practice there have been such disadvantages that the accuracy in the ratio between the divided flows is largely influenced by the accuracies of finishing of the jet needle and jet orifice used in the flow division control means, and further, the accuracy in control is decreased by gaps formed within the interlocking mechanism because the flow division control means is interlocked with the main and auxiliary throttle valves by means of links and the like.